Electromagnetic waves - Microwaves for Grade 10 .ppt

quarter2

2. Microwaves have smaller
wavelengths than radio waves.
They are used in
satellite communications,
radar,
television transmission and
cooking.

4. Microwaves can penetrate the atmosphere
of the earth. This is the reason why they
are used for satellite communications.

5. Communication satellites travel around the
earth at an altitude of 35, 000 km above
the equator. They move at a speed of 11
300 km/h
and revolve
around the earth
every 24 hours,
the same rate
as the rotation of
the earth.

6. Microwaves signals are transmitted by
an antenna to a satellite which
amplifies and re-transmits the signal
to an antenna in other parts of the
world.
This is how we communicate with the
rest of the world.

7. A radar system is consists of an antenna,
transmitter, and a receiver.
The antenna whirls around continuously to
scan the surrounding area.

8. The transmitter sends
out a narrow beam of
microwaves in short
pulses. A distant
object reflects some
of the signal back to
the receiver.

9. Microwaves are used to transmit
television news coverage from
mobile broadcast vehicles back to
the station.
This is how news are broadcasted
and watched live around the
world.

11. A cell phone is a radio transmitter and
receiver that uses microwaves.
Cellular phones depend on overlapping
network of cells or areas of land several
kilometres in diameter. Each cell has its
tower that receives and sends microwave
signals.

13. In a microwave oven, foods absorb certain
microwave frequencies very strongly. The
microwaves penetrate the food being
heated. It will agitate the water molecules
within the food, thus creating molecular
friction which thenproduces heat that will
cook it.